A series of new medical reports concludes that the saccharin-cancer scare of the 1970s was overstated and that, except for certain special groups, such as children, people who use modest amounts of the artificial sweetener have "little cause for concern" about cancer.

The studies' major finding is that "there is no saccharin-induced epidemic of bladder cancer in this country," Dr. Robert Hoover, environmental studies chief of the National Cancer Institute, says in today's New England Journal of Medicine.

The dieter who uses a packet or two of saccharin a day in coffee, or the diabetic who drinks a diet drink, he adds, "can be assured" that the excess risk of cancer, "if present at all, is quite small and little cause for concern."

The main risk, it appears, is among children and youths, heavy saccharin users or diet-drinkers, users who smoke and women who are pregnant.

The New England journal summarizes a new Harvard School of Public Health study that failed to find any general pattern of artificial sweetner use in 592 Bostonians with bladder cancer.

Science magazine Friday is to report similar results among 367 patients in six cities who were studied by Dr. Ernst Wynder and Steven Stellman of the American Health Foundation.

A Food and Drug Administration official yesterday said FDA is doing nothing to prepare any new anti-saccharin rules. A congressional moratorium on any FDA saccharin ban expired last May. Last year FDA officials were still speaking of possible new actions against the sweetner.

The latest studies confirm a largely similar result in a December National Cancer Institute report on more than 3,000 cancer patients.

None of these studies proves saccharin to be completely safe. Either the Harvard or NCI study or both found some excess risk among smokers, and among users of more than two diet drinks or their equivalent daily. A packet of saccharin contains about 30 milligrams; a diet drink about 80.

Almost all authorities continue to be alarmed by the heavy consumption of diet drinks by many youngsters and women who may become pregnant, and the heavy advertising of these drinks.

Taken together, however, the recent studies could take even more of the sting out of the once-fervent federal anti-saccharin drive.

The House voted last year to extend the moratorium on new FDA action. "We fully expect" the Senate to concur, said Wayne Pines, FDA associate commissioner for public affairs. "Therefore, we are not going to expend futher resources in developing regulations on saccharin."

Pines said the FDA still feels that saccharin is "a weak carcinogen," but a carcinogen nonetheless, and, "We are still concerned with its consumption by so many people."

The most damning evidence against saccharin has come from studies showing that it causes or helps cause bladder cancers in animals. And one Canadian study indicated a 60 percent increased risk of bladder cancer among saccharin-using men.

The situation today is that further human studies have failed to confirm any such link in the population as a whole.

The NCI did find a 60 percent increased risk among "heavy" saccharin users, two or more eight-ounce diet drinks or six or more servings a day of a sugar substitute. Women, for example, who ordinarily have a yearly rate of five cases of bladder cancer per 100,000 may have eight cases with heavy saccharin use.

The same study found an unmeasurable degree of increased risk among saccharin-using men who smoked two or more cigarette packs daily, or women who smoked one or more.

Harvard's Dr. Allan Morrison and Julie Buring said today that they found no excess bladder cancer risk in either men or women saccharin users in general. But they too found extra risk among women who use diet beverages in quantity.

Where NCI found some extra risk among heavy smokers, Harvard doctors observed no such effect.

This does not exonerate smoking. What it does show, Hoover writes, is that whatever risk is associated with saccharin is a weak one, which doesn't produce enough cases for accurate measurement in a sample of hundreds of persons.

Just the same, he adds, when all the evidence, human and animal, is weighed against the lack of evidence of saccharin benefits, any use at all by non-diabetic children or pregnant women is ill-advised. So, he says, is heavy use by women of child-bearing age, and excessive use by anyone.

Then-FDA commissioner Donald Kennedy and four members of a National Academy of Sciences food safety panel told a congressional subcommittee last year that saccharin "probably" causes some bladder cancers. They said it should at least be denied to the millions of children who are drinking it.